[Right way to update target element of a tween]

I have one element with a animation and one element that should adopt the same animation. Now I can take the tween object and write into the _targets property, which works fine for now. But as the underscore indicates, that _targets should be treated as a private property, the trick is actually forbidden.

 

Is there a right way to change _targets then?

[Animating SVG <symbol> does not update <use>]

Why for example animating the fill attribute of an element inside a <symbol> has no effect but manipulating it once using jQuery's attr() function has?

See the Pen OyXaYY by MariusUniUlm (@MariusUniUlm) on CodePen